Light pollution is a type of pollution that climaxes in cities and occurs increasingly away from them, due to the increase of artificial lighting and inappropriate lighting design (selection of luminaires, aiming, illuminance/luminance levels, and spectral characteristics). Increasingly, light pollution also affects the countryside due to local lighting but also distant lighting propagating from urban areas. This has a significant impact on ecosystems and astronomical observing sites. This work analyzes the main facts about light pollution (causes, impact, and solutions) and studies the methods, parameters, and special requirements for planning of light pollution protected areas. This dark sky park planning methodology is implemented as a case study in mount Parnon which has been selected due to its significance as a Natura 2000 protected area and because it is Greece’s most popular astronomical observing site. Mount Parnon is located close to two major cities as well as significant highways, however the site itself remains dark due to its sparse population. Planning a dark sky park involves a complete study of facts regarding the specific site. Existing lighting installations are surveyed in detail by recording types of luminaires and lamps and recording their positions in a map. Lighting illuminance levels are measured by photometers and spectra are analyzed using a spectrometer. Sky brightness levels measurements are performed using specialized photometers and light pollution origins are traced using wide-field photography. Finally, a proposal is made for a dark sky park scheme suited to the specific case of the site.